Finite element analysis based model to study the electric field distribution and leakage current in PV modules under high voltage bias

Abstract

The maximum system voltage for Photovoltaic systems is 1000 V in US. Some modules are designed to operate even at 1500 V, which is the limit for IEC low voltage systems. The high voltage bias between the cell circuit and frame of the module leads to a leakage current flowing through the insulation of the module to the ground. Over time, this leakage current causes migration of various species to and from the cell circuit, can result in slow degradation of the performance of PV module. It is important to understand the electric field distribution and leakage current pathways in the PV modules in order to study the system voltage induced degradation of PV modules. The leakage current from the PV modules deployed outdoor and under high voltage bias strongly varies with the environmental conditions. The lumped resistance models described in literature that attempt to explain the leakage current flow through the PV module do not provide adequate information about the distribution of leakage current through different layers of insulation present in the PV modules. In this paper, a Finite Element Analysis (FEA) based model for the insulation of PV module is described. It yields useful information about the distribution of electric field, potential and leakage current flowing through different layers of module. The model is also used to predict and analyze the changes in leakage current with changes in module packaging materials and grounding configurations.